Early weaning negatively impacts pig performance through disruption of the intestinal structure, barrier function, and immune response. These impacts are exacerbated by subsequent stressors like disease challenges. A study of over 140,000 pigs across 5 years found that every additional day of weaning age from 18-24 days reduced mortality by 0.56% on average and improved average daily gain by 7.8 grams under normal health conditions. The negative effects of early weaning were more pronounced during times of poor health status on the sow farm.

1. InfluenceofWeanAgeandDisease
ChallengeonProgenyLife-timePerformance
D.S.Rosero*,T.DonovanandR.D.Boyd
TheHanorCompany,Franklin,KYUSA

2. WEANING: myriad of stressors for the young pig!
abrupt maternal separation
socialhierarchy
transportation
handling
different food source
co-mingling
different litters
physical environment pathogens
antigens

3. WEANING: Disruption of GI structure and function
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Villousheight,µm
Days after weaning
Unweaned
Weaned
Hampson, 1986; Res Vet Sci 40:32-40; Lindemann et al., 1986; J Anim Sci 62:1298-1307
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-8 -6 -4 -2 0 2 4 6 8 10 12 14 16
Enzymeactivity(X10000)
Days after weaning
Unweaned Unweaned
Weaned Weaned
Amylase
Reduced digestive enzyme activityVilli atrophy
Lipase
(hypothetical)

4. PARADIGM: Early-life Stress and GI disease development
Early weaning
Plasticity
Stresssensitivity
DiseaseRiskandSeverity
Pohl, Medland, and Moeser 2015; Am J Physiol-GI 309:G927-G941
Life-time
Barrier function is
compromised

5. EARLY-WEANING STRESS: disruption of intestinal barrier
Ussing Chamber Technique
3H-Mannitol
14C-Inulin Supernatant
↑ Flux = ↓ barrier function
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3H-Mannitolflux,µmol-cm2h
Weaning Age
Smith et al., 2010; Am J Physiol GI 298: G352–G363

6. EARLY-WEANING STRESS: long-lasting impact on barrier function
Ussing Chamber Technique
3H-Mannitol
14C-Inulin Supernatant
↑ Flux = ↓ barrier function
Smith et al., 2010; Am J Physiol GI 298: G352–G363
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0 20 40 60 80 100 120 140 160 180
3H-Mannitolflux,µmol-cm2h(x10-3)
Days after weaning
Early weaning
Late weaning

7. EARLY-WEANING STRESS: Subsequent stressors
Impact of Wean Age on intestinal barrier function and immune response to E. coli challenge
McLamb et al., 2013; PloS ONE, 8:e59838
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16 18 20
Mucosal-to-Serosalflux,µgFD4/min
Weaning Age
Control
ETEC Challenge
c c
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c
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a
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16 18 20
Neutrophils/HPF
Weaning Age
Intestinal Permeability Immune response

8. EARLY-WEANING: myriad of stressors with long-lasting impact
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0 10 20 30 40 50 60 70
BW,lbs
Age, d
Late weaned
Early weaned
Weaning
 Early weaning negatively impact:
• Intestinal structure
• Brush border enzyme activity
• Intestinal barrier function
• Immune response
 Impact is exacerbated by other stressors:
• Management – mixing and crowding
• Infectious challenges
…. and many more!
Response is immediate, acute and long-lasting

9. Impact of weaning age on performance of pigs
500
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750
12 15 18 21 15.5 18.5 21.5
ADG(weaningtod153-156),g
Weaning Age
Linear, P < 0.001
Linear, P < 0.001
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2
4
6
8
10
12
12 15 18 21 15.5 18.5 21.5
Wean-FinishMortality,%
Weaning Age
Linear, P < 0.001
Linear, P = 0.03
Main et al., 2004; J Anim Sci 82:1499-1507
Growth rate Mortality
n = 1,920 & 3,000 pigs
Trial 1 Trial 2 Trial 1 Trial 2
n = 1,920 & 3,000 pigs

10. PURPOSE
 To investigate and quantify the impact of weaning age on pig performance within a
multisite production system
• Impact of weaning age during health challenge events
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1/1/2010 7/20/2010 2/5/2011 8/24/2011 3/11/2012 9/27/2012 4/15/2013 11/1/2013 5/20/2014 12/6/2014
AverageWeaningAgeperweek
Wean Date
Active PRRS Active PEDV
Weaning Age of Groups of Pigs by Weaning Date

11. METHODS
 Sow Farm: DN Sow Farm (2,800 sows) located in North Carolina
 Pig groups: 143 wean-to-finish groups (1,932 ± 793 pigs per group) located in Iowa
 Weaning dates: Jan 2010 to Dec 2014
 Weaning age:
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Groupsofpigs,n
Weaning Age

12. METHODS (Cont.)
 Calculations:
• Growth performance data (ADG, ADFI, FCR)
were standardized to a final weight of 136 kg
 Production records:
• Sow farm: weekly wean age distribution, monthly performance
• Close-outs: placement and end dates, start and end weights, feed per head, mortality, off-grade pigs
 Health Status records:
• PRRS, Jan to March of 2010
• PEDV, Jan and Feb of 2014
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Finalbodyweight,kg
Age, days
136 kg

13. METHODS (Cont.)
 Statistics Description
• Models: linear and non-linear regressions
• Close-out group was the experimental unit.
• Normally distributed and fitted linear models: ADG, FCR and days to final weight
• Non-normally distributed and non-linear models: mortality and off-grade pigs
• Goodness of fit of models
o Linear: RMSE and R-square
o Non-linear: Pearson test and the corrected Akaike Information Criterion (AICc)

14. WTF Mortality: what variables explain variation?
 Weaning age and health status explain a great proportion of variation
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Weaning Age Health Status WeanDate Facility Type
Correlationcoefficient,r
Variables
**
*

15. WTF Mortality: impact of weaning age
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5
10
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25
17 18 19 20 21 22 23 24 25
Mortality,%
Weaning age, days
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 % = 𝐸𝐸𝐸𝐸𝐸𝐸 3.73 + (−0.092 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝑊𝑊 𝐴𝐴𝐴𝐴𝐴𝐴)
P < 0.001

16. WTF Mortality: impact of weaning age and health
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Mortality,%
Weaning Age, d
18 19 20 21 22 23 24
Weaning Age, d
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 % = 𝐸𝐸𝐸𝐸𝐸𝐸 4.10 + (−0.109 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝐴𝐴𝐴𝐴𝐴𝐴) 𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 % = 𝐸𝐸𝐸𝐸𝐸𝐸 3.05 + (−0.061 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝐴𝐴𝐴𝐴𝐴𝐴)
P = 0.003 P = 0.04
Poor health Good health
Δ = 0.87
Δ = 0.51
Δ = 0.42
Δ = 0.31

17. Growth rate: impact of weaning age
𝐴𝐴𝐴𝐴𝐴𝐴 𝑔𝑔 = 535.3 + (7.8 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝑊𝑊 𝑎𝑎𝑎𝑎𝑎𝑎)
P < 0.001
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750
800
17 18 19 20 21 22 23 24 25
ADG,g
Weaning age, d

18. 18 19 20 21 22 23 24
Weaning Age, d
620
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660
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760
18 19 20 21 22 23 24
ADG,g
Weaning Age, d
Growth rate: impact of weaning age and health
𝐴𝐴𝐴𝐴𝐴𝐴 𝑔𝑔 = 504.2 + (9.3 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝑎𝑎𝑎𝑎𝑎𝑎) 𝐴𝐴𝐴𝐴𝐴𝐴 𝑔𝑔 = 545.8 + (7.4 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝑊𝑊 𝑎𝑎𝑎𝑎𝑎𝑎)
P = 0.003 P = 0.04
Poor health Good health

19. WTF Mortality and off-grades: non-linear models
Parameters
Variables , % a b AICc Goodness of Fit (Pearson) Prob>ChiSq
Off-grade pigs 1.80 -0.044 419 0.0035 0.2321
Mortality 3.73 -0.092 626 0.0004 <0.0001
Poor Health
Off-grade pigs 2.31 -0.064 284 0.0985 0.1630
Mortality 4.10 -0.109 290 <0.0001 0.0026
Good Health
Off-grade pigs 1.66 -0.045 171 0.0008 0.5102
Mortality 3.05 -0.061 385 0.5370 0.0387
𝑦𝑦 = 𝐸𝐸𝐸𝐸𝐸𝐸 𝒂𝒂 + (𝒃𝒃 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝑊𝑊 𝐴𝐴𝐴𝐴𝐴𝐴)

20. Growth performance: linear models
𝑦𝑦 = 𝒂𝒂 + (𝒃𝒃 × 𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊𝑊 𝑊𝑊 𝐴𝐴𝐴𝐴𝐴𝐴)
Parameters
Variables a b RMSE R-square P-value
Days to 136 kg 249.8 -2.0 10.139 0.1020 0.0006
ADG, g 535.3 7.8 0.083 0.1083 0.0004
FCR 2.854 -0.015 0.116 0.0437 0.0276
Poor Health
Days to 136 kg 259.0 -2.5 9.312 0.1445 0.0109
ADG, g 504.2 9.3 0.075 0.1528 0.0087
FCR 2.788 -0.011 0.140 0.0137 0.4495
Good Health
Days to 136 kg 246.2 -1.9 10.677 0.069 0.0211
ADG, g 545.8 7.4 0.089 0.0756 0.0162
FCR 2.701 -0.008 0.103 0.0139 0.3104

21. Rate of Change as weaning age increases (18-24 d)
Variable All Poor Health Good Health
Days to 136 kg -2.0 -2.5 -1.9
ADG, g 7.8 9.3 7.4
FCR -0.014 -0.011 -0.008
Off-grade pigs, % -0.11 -0.17 -0.09
Mortality, % -0.56 -0.68 -0.36

22. CONCLUSIONS
 Weaning age and health status of the sow farm greatly impacted the life-time
performance of pigs overtime (2010 - 2014)
 The negative impact of early weaning was more profound under health
challenge conditions (poor health)
 On this “healthy” sow farm (few health challenge events) every additional
weaning day (18 to 24 d) reduced the mortality by 0.56% and improved the
growth rate of pigs by 7.8 g/d

23. THANK YOU!